freebsd/usr.sbin/sysrc/sysrc.8

.\" Copyright (c) 2011-2013 Devin Teske
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.\" $FreeBSD$
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.Dd Nov 20, 2013
.Dt SYSRC 8
.Os
.Sh NAME
.Nm sysrc
.Nd safely edit system rc files
.Sh SYNOPSIS
.Nm
.Op Fl cdDeFhinNqvx
.Op Fl f Ar file
.Op Fl j Ar jail | Fl R Ar dir
.Ar name Ns Op = Ns Ar value
.Ar ...
.Nm
.Op Fl cdDeFhinNqvx
.Op Fl f Ar file
.Op Fl j Ar jail | Fl R Ar dir
.Fl a | A
.Sh DESCRIPTION
The
.Nm
utility retrieves
.Xr rc.conf 5
variables from the collection of system rc files and allows processes with
appropriate privilege to change values in a safe and effective manner.
.Pp
The following options are available:
.Bl -tag -width indent+
.It Fl a
Dump a list of all non-default configuration variables.
.It Fl A
Dump a list of all configuration variables
.Pq incl. defaults .
.It Fl c
Check if the value will change when assigning a new value.
If verbose
.Pq see Dq Fl v
prints a message stating whether a change would occur.
Exits with success if no change is necessary, else returns error status.
.It Fl d
Print a description of the given variable.
.It Fl D
Show default value(s) only (this is the same as setting RC_CONFS to NULL or
passing `-f' with a NULL file-argument).
.It Fl e
Print query results as
.Xr sh 1
compatible syntax
.Pq for example, Ql var=value .
Ignored if either
.Ql Fl n
or
.Ql Fl F
is specified.
.It Fl f Ar file
Operate on the specified file(s) instead of the files obtained by reading the
.Sq rc_conf_files
entry in the
.Ev RC_DEFAULTS
file.
This option can be specified multiple times for additional files.
.It Fl F
Show only the last
.Xr rc.conf 5
file each directive is in.
.It Fl h
Print a short usage message to stderr and exit.
.It Fl -help
Print a full usage statement to stderr and exit.
.It Fl i
Ignore unknown variables.
.It Fl j Ar jail
The
.Ar jid
or name of the
.Ar jail
to operate within
.Pq overrides So Fl R Ar dir Sc ; requires Xr jexec 8 .
.It Fl n
Show only variable values, not their names.
.It Fl N
Show only variable names, not their values.
.It Fl q
Quiet.
Ignore previous occurrences of
.Fl v
flag.
.It Fl R Ar dir
Operate within the root directory
.Pq Sq Ar dir
rather than
.Pq Sq / .
.It Fl v
Verbose.
Print the pathname of the specific
.Xr rc.conf 5
file where the directive was found.
.It Fl -version
Print version information to stdout and exit.
.It Fl x
Remove variable(s) from specified file(s).
.El
.Pp
This utility works similar to
.Xr sysctl 8 .
It shares the `-e' and `-n' options
.Pq detailed above
and also has the same
.Ql name[=value]
syntax for querying/setting configuration options.
.Pp
However, while
.Xr sysctl 8
serves to query/modify MIBs in the entrant kernel,
.Nm
instead works on values in the system
.Xr rc.conf 5
configuration files.
.Pp
The list of system configuration files is configured in the file
.Ql /etc/defaults/rc.conf
within the variable
.Ql rc_conf_files ,
which by-default contains a space-separated list of pathnames.
On all FreeBSD
systems, this defaults to the value "/etc/rc.conf /etc/rc.conf.local".
Each
pathname is sourced in-order upon startup.
It is in the same fashion that
.Nm
sources the configuration files before returning the value of the given
variable.
.Pp
When supplied a variable name,
.Nm
will return the value of the variable.
If the variable does not appear in any
of the configured
.Ql rc_conf_files ,
an error is printed and error status is returned.
.Pp
When changing values of a given variable, it does not matter if the variable
appears in any of the
.Ql rc_conf_files
or not.
If the variable does not appear in any of the files, it is appended to
the end of the first pathname in the
.Ql rc_conf_files
variable.
Otherwise,
.Nm
will replace only the last-occurrence in the last-file found to contain the
variable.
This gets the value to take effect next boot without heavily
modifying these integral files (yet taking care not to allow the file to
grow unwieldy should
.Nm
be called repeatedly).
.Sh ENVIRONMENT
The following environment variables are referenced by
.Nm :
.Bl -tag -width ".Ev RC_DEFAULTS"
.It Ev RC_CONFS
Override default
.Ql rc_conf_files
.Pq even if set to NULL .
.It Ev RC_DEFAULTS
Location of
.Ql /etc/defaults/rc.conf
file.
.El
.Sh DEPENDENCIES
The following standard commands are required by
.Nm :
.Pp
.Xr awk 1 ,
.Xr cat 1 ,
.Xr chmod 1 ,
.Xr env 1 ,
.Xr grep 1 ,
.Xr jls 1 ,
.Xr mktemp 1 ,
.Xr mv 1 ,
.Xr rm 1 ,
.Xr sh 1 ,
.Xr stat 1 ,
.Xr tail 1 ,
.Xr chown 8
and
.Xr jexec 8 .
.Sh FILES
.Bl -tag -width ".Pa /etc/defaults/rc.conf" -compact
.It Pa /etc/defaults/rc.conf
.It Pa /etc/rc.conf
.It Pa /etc/rc.conf.local
.El
.Sh EXAMPLES
Below are some simple examples of how
.Nm
can be used to query certain values from the
.Xr rc.conf 5
collection of system configuration files:
.Pp
.Nm
sshd_enable
.Dl returns the value of $sshd_enable, usually YES or NO .
.Pp
.Nm
defaultrouter
.Dl returns IP address of default router Pq if configured .
.Pp
Working on other files, such as
.Xr crontab 5 :
.Pp
.Nm
-f /etc/crontab MAILTO
.Dl returns the value of the MAILTO setting Pq if configured .
.Pp
In addition to the above syntax,
.Nm
also supports inline
.Xr sh 1
PARAMETER expansion for changing the way values are reported, shown below:
.Pp
.Nm
\&'hostname%%.*'
.Dl returns $hostname up to (but not including) first `.' .
.Pp
.Nm
\&'network_interfaces%%[$IFS]*'
.Dl returns first word of $network_interfaces .
.Pp
.Nm
\&'ntpdate_flags##*[$IFS]'
.Dl returns last word of $ntpdate_flags (time server address) .
.Pp
.Nm
usbd_flags-"default"
.Dl returns $usbd_flags or "default" if unset or NULL .
.Pp
.Nm
cloned_interfaces+"alternate"
.Dl returns "alternate" if $cloned_interfaces is set .
.Pp
.Nm
\&'#kern_securelevel'
.Dl returns length in characters of $kern_securelevel .
.Pp
.Nm
\&'hostname?'
.Dl returns NULL and error status 2 if $hostname is unset Pq or if set, returns the value of $hostname with no error status .
.Pp
.Nm
\&'hostname:?'
.Dl returns NULL and error status 2 if $hostname is unset or NULL Pq or if set and non-NULL, returns value without error status .
.Sh LIMITATIONS
The
.Nm
utility presently does not support the
.Ql rc.conf.d
collection of system configuration files
.Pq which requires a service name to be known during execution .
.Pp
This will be corrected by a future enhancement.
.Sh SEE ALSO
.Xr jls 1 ,
.Xr rc.conf 5 ,
.Xr jail 8 ,
.Xr jexec 8 ,
.Xr rc 8 ,
.Xr sysctl 8
.Sh HISTORY
A
.Nm
utility first appeared in
.Fx 9.2 .
.Sh AUTHORS
.An Devin Teske Aq dteske@FreeBSD.org
.Sh THANKS TO
Brandon Gooch, Garrett Cooper, Julian Elischer, Pawel Jakub Dawidek,
Cyrille Lefevre, Ross West, Stefan Esser, Marco Steinbach, and Jilles Tjoelker
for suggestions and help.